Quiet landing gear door

ABSTRACT

A quiet landing gear door and methods are presented. A landing gear door comprises a trailing edge and a leading edge and is operable to deploy to a landing gear door deployed position. A door flap comprises the trailing edge and is hinged to the landing gear door. The door flap deflects toward a landing gear strut to a door flap deployed position in response to deployment of the landing gear door. A leading edge section comprises the leading edge and is coupled to the door flap. The leading edge section deflects toward the landing gear strut to a leading edge deployed position in response to deployment of the landing gear door.

FIELD

Embodiments of the present disclosure relate generally to landing gearstructures. More particularly, embodiments of the present disclosurerelate to landing gear doors.

BACKGROUND

Increasing aircraft noise regulations necessitate reductions in aircraftnoise. While engine noise is generally considered a main source ofaircraft noise during take-off, interaction of air turbulence withaircraft structures may also be a source of noise. Furthermore, during alow engine power landing, interaction of the air turbulence with theaircraft structures may be a primary source of noise.

SUMMARY

A quiet (low noise or reduced noise) landing gear door and methods arepresented. A landing gear door comprising a trailing edge and a leadingedge deploys to a landing gear door deployed position. A door flaphinged to the trailing edge deflects toward a landing gear strut to adoor flap deployed position in response to deployment of the landinggear door. A leading edge section deflects toward a landing gear strutto a leading edge deployed position in response to deployment of thelanding gear door.

In this manner, embodiments of the disclosure provide a quiet landinggear door that reduces noise generated by interaction of a landing gearwake with an aerodynamic surface.

In an embodiment, a quiet landing gear door comprises a landing geardoor, a door flap, and a leading edge section. The landing gear doorcomprises a trailing edge and a leading edge and deploys to a landinggear door deployed position. The door flap comprises the trailing edgeand is hinged to the landing gear door. The door flap deflects toward alanding gear strut to a door flap deployed position in response todeployment of the landing gear door. The leading edge section comprisesthe leading edge and is coupled to the door flap. The leading edgesection deflects toward the landing gear strut to a leading edgedeployed position.

In another embodiment, a method for reducing landing gear wake-wing flapinteraction noise deploys a landing gear door comprising a trailing edgeand a leading edge. The method further deflects toward a landing gearstrut a leading edge section comprising the leading edge and coupled tothe landing gear door. The method also deflects toward the landing gearstrut a door flap comprising the trailing edge and hinged to the landinggear door. The method further reduces a flow velocity on a pressure sideof the landing gear door due deflecting the bullnose and the door flap.

In a further embodiment, a method for configuring a quiet landing geardoor, configures a landing gear door to deploy to a landing geardeployed position. The method couples a leading edge section and a doorflap to the landing gear door. The method then configures the leadingedge section and the door flap to deflect toward a landing gear strut inthe landing gear deployed position to reduce a local flow speed near thelanding gear strut and minimize a wake impinging on a pressure side ofan aerodynamic surface of an aircraft such that a landing gear noise anda landing gear wake-aerodynamic surface interaction noise are reduced.

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the detaileddescription. This summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used as an aid in determining the scope of the claimed subjectmatter.

BRIEF DESCRIPTION OF DRAWINGS

A more complete understanding of embodiments of the present disclosuremay be derived by referring to the detailed description and claims whenconsidered in conjunction with the following figures, wherein likereference numbers refer to similar elements throughout the figures. Thefigures are provided to facilitate understanding of the disclosurewithout limiting the breadth, scope, scale, or applicability of thedisclosure. The drawings are not necessarily made to scale.

FIG. 1 is an illustration of a flow diagram of an exemplary aircraftproduction and service methodology.

FIG. 2 is an illustration of an exemplary block diagram of an aircraft.

FIG. 3 is an illustration of an exemplary perspective view of a portionof an aircraft showing a landing gear structure comprising a landinggear door coupled thereto according to an embodiment of the disclosure.

FIG. 4 is an illustration of an exemplary section view of an existinglanding gear door showing a landing gear wake that can impinge on fluiddynamic surfaces thereby generating landing gear wake-wing flapinteraction noise.

FIG. 5 is an illustration of an exemplary section view of a landing geardoor in a deployed position according to an embodiment of thedisclosure.

FIGS. 6-12 are illustrations of section views showing a free stream flowover a landing gear door at various door flap deflection anglesaccording to an embodiment of the disclosure.

FIG. 13 is an illustration of a graph showing a landing gear door wakedeficit at various door flap deflection angles according to anembodiment of the disclosure.

FIG. 14 is an illustration of a graph showing a lift coefficient C_(L)of the landing gear door vs. door flap deflection angles in degreesaccording to an embodiment of the disclosure.

FIG. 15 is an illustration of a graph showing a landing gear wake-wingflap interaction noise reduction due to deploying a landing gear dooraccording to an embodiment of the disclosure compared to a landing gearwake-wing flap interaction noise generated when using an existinglanding gear door.

FIG. 16 is an illustration of an exemplary block diagram of a landinggear door system according to an embodiment of the disclosure.

FIG. 17 is an illustration of an exemplary flowchart showing a processfor reducing landing gear wake-wing flap interaction noise according toan embodiment of the disclosure.

FIG. 18 is an illustration of an exemplary flowchart showing a processfor configuring a quiet landing gear door according to an embodiment ofthe disclosure.

DETAILED DESCRIPTION

The following detailed description is exemplary in nature and is notintended to limit the disclosure or the application and uses of theembodiments of the disclosure. Descriptions of specific devices,techniques, and applications are provided only as examples.Modifications to the examples described herein will be readily apparentto those of ordinary skill in the art, and the general principlesdefined herein may be applied to other examples and applications withoutdeparting from the spirit and scope of the disclosure. The presentdisclosure should be accorded scope consistent with the claims, and notlimited to the examples described and shown herein.

Embodiments of the disclosure may be described herein in terms offunctional and/or logical block components and various processing steps.It should be appreciated that such block components may be realized byany number of hardware, software, and/or firmware components configuredto perform the specified functions. For the sake of brevity,conventional techniques and components related to aircraft landing geardoor, aircraft landing gear door operation, and other functional aspectsof systems described herein (and the individual operating components ofthe systems) may not be described in detail herein. In addition, thoseskilled in the art will appreciate that embodiments of the presentdisclosure may be practiced in conjunction with a variety of hardwareand software, and that the embodiments described herein are merelyexample embodiments of the disclosure.

As would be apparent to one of ordinary skill in the art after readingthis description, the following are examples and embodiments of thedisclosure and are not limited to operating in accordance with theseexamples. Other embodiments may be utilized and structural changes maybe made without departing from the scope of the exemplary embodiments ofthe present disclosure.

Referring more particularly to the drawings, embodiments of thedisclosure may be described in the context of an exemplary aircraftmanufacturing and service method 100 (method 100) as shown in FIG. 1 andan aircraft 200 as shown in FIG. 2. During pre-production, the method100 may comprise specification and design 104 of the aircraft 200, andmaterial procurement 106. During production, component and subassemblymanufacturing 108 (process 108) and integration of system 110 (systemintegration 110) of the aircraft 200 takes place. Thereafter, theaircraft 200 may go through certification and delivery 112 in order tobe placed in service 114. While in service by a customer, the aircraft200 is scheduled for routine maintenance and service 116 (which may alsocomprise modification, reconfiguration, refurbishment, and so on).

Each of the processes of method 100 may be performed or carried out by asystem integrator, a third party, and/or an operator (e.g., a customer).For the purposes of this description, a system integrator may comprise,for example but without limitation, any number of aircraft manufacturersand major-system subcontractors; a third party may comprise, for examplebut without limitation, any number of vendors, subcontractors, andsuppliers; and an operator may comprise, for example but withoutlimitation, an airline, leasing company, military entity, serviceorganization; and the like.

As shown in FIG. 1, the aircraft 200 produced by the method 100 maycomprise an airframe 218 with a plurality of systems 220 and an interior222. Examples of high-level systems of the systems 220 comprise one ormore of a propulsion system 224, an electrical system 226, a hydraulicsystem 228, an environmental system 230, and a quiet (low noise) landinggear door 232. Any number of other systems may also be included. In thisdocument, quiet may mean, for example but without limitation, low noise,reduced noise, or attenuated noise.

Apparatus and methods embodied herein may be employed during any one ormore of the stages of the method 100. For example, components orsubassemblies corresponding to production of the process 108 may befabricated or manufactured in a manner similar to components orsubassemblies produced while the aircraft 200 is in service. Inaddition, one or more apparatus embodiments, method embodiments, or acombination thereof may be utilized during production stages of theprocess 108 and the system integration 110, for example, bysubstantially expediting assembly of or reducing the cost of an aircraft200. Similarly, one or more of apparatus embodiments, methodembodiments, or a combination thereof may be utilized while the aircraft200 is in service, for example and without limitation, to maintenanceand service 116.

FIG. 3 is an illustration of an exemplary perspective view 300 of aportion of an aircraft 200 showing a landing gear structure 302comprising a landing gear door 304 coupled thereto according to anembodiment of the disclosure. The landing gear door 304 may be coupledto an aircraft such as the aircraft 200 and may comprise a leading edgesection 306, and a door flap 308.

The landing gear door 304 comprises a trailing edge 310 and a leadingedge 312 and is configured to deploy to a main landing gear doordeployed position 314 as shown in FIG. 3. The landing gear door 304 maybe coupled to the landing gear structure 302 of the aircraft 200.

The door flap 308 comprises the trailing edge 310 and is hinged to thelanding gear door 304 via a trailing edge hinge line 316. The door flap308 is configured to deflect in a direction 330 toward a landing gearstrut 322 to a door flap deployed position 502 (e.g., as shown in FIG.5) in response to deployment of the landing gear door 304. The door flap308 may be located, for example but without limitation, at about 50percent to about 60 percent of a chord plane 332 of the landing geardoor 304, or other location on the chord plane 332 suitable foroperation of the landing gear door 304. The door flap 308 may also becoupled to the landing gear door 304 via a shape memory alloy (SMA)material that can deflect in response to a temperature change, or viaother coupling means that can position the door flap 308 at a deflectedposition when the landing gear door 304 is deployed.

The leading edge section 306 comprises the leading edge 312 and iscoupled to the landing gear door 304. The leading edge section 306 isconfigured to deflect in the direction 330 toward the landing gear strut322 to a leading edge deployed position 504 (e.g., as shown in FIG. 5)in response to deployment of the landing gear door 304. The leading edgesection 306 may comprise, for example but without limitation, a bullnosefixedly coupled to the landing gear door 304, a drooped leading edgehinged to the landing gear door 304 via a leading edge hinge line 318, adrooped leading edge coupled to the landing gear door 304 via a shapememory alloy (SMA) material that can deflect in response to atemperature change, or other leading edge section that can be positionedat a deflected position when the landing gear door 304 is deployed.

In operation, when the landing gear door 304 is in the main landing geardoor deployed position 314, the leading edge section 306 in the leadingedge deployed position 504, and the door flap 308 in the door flapdeployed position 502 a flow circulation is generated around the landinggear structure 302, which reduces a flow velocity on a side of thelanding gear strut 322.

In this manner, landing gear wake-wing flap interaction caused by alanding gear wake 402 (FIGS. 4 and 5) from the landing gear strut 322and the landing gear braces 324 impinging on a pressure side 326 of thewing flap 328 is reduced thereby reducing noise caused by suchinteraction.

Reducing the landing gear wake-wing flap interaction increaseseffectiveness of the wing flap 328 by reducing a strength of the landinggear wake 402 from the landing gear door 304 impinging on the pressureside 326 of the wing flap 328. Additionally, reducing the landing gearwake-wing flap interaction reduces a risk of unexpected buffet of thewing flap 328.

FIG. 4 is an illustration of an exemplary section view of an existinglanding gear door 408 showing the landing gear wake 402 that can impingeon fluid dynamic surfaces such as on the pressure side 326 of the wingflap 328. The landing gear wake 402 interacts with fluid dynamicsurfaces such as on the wing flap 328 and may generate a landing gearwake-wing flap interaction noise. The fluid dynamic surfaces maycomprise, for example but without limitation, aerodynamic surfaces suchas a flap, a spoiler, an aileron, or other fluid dynamic surfaces cableof moving through a fluid such as air and/or water.

FIG. 5 is an illustration of an exemplary section view of the door flap308 in the door flap deployed position 502 and the leading edge section306 in a leading edge deployed position 504 according to an embodimentof the disclosure. Deflecting the door flap 308 and the leading edgesection 306 reduces a local flow velocity 508 on a pressure side 506 ofthe door flap 308 near the landing gear strut 322 and the landing gearbraces 324. Reducing the local flow velocity 508 or local speed of thelocal flow velocity 508 near the landing gear strut 322 minimizes thelanding gear wake 402 impinging on the pressure side 326 of anaerodynamic surface such as the wing flap 328 of the aircraft 200.

In this manner, the landing gear wake 402 (FIGS. 4 and 5) impinging onthe pressure side 326 of the wing flap 328 is reduced, thereby reducinglanding gear wake-wing flap interaction noise generated by interactionof the landing gear wake 402 from the landing gear strut 322 and thelanding gear braces 324 with the wing flap 328. Reducing the local flowvelocity also reduces a landing gear strut noise of the landing gearstrut 322.

Since landing gear noise generally increases in proportion to (Mach)⁵, asmall reduction in the local flow velocity 508 can have a significantimpact on landing gear door noise and landing gear wake-aerodynamicsurface interaction noise. The landing gear door wake-wing flapinteraction noise and landing gear noise may be reduced by, for example,about 2 dB to about 5 dB, which for gear dominated airframe noise can besignificant.

FIGS. 6-12 are illustrations of section views showing a free stream flow602 over the landing gear door 304 (main landing gear door 304) at,without limitation, 8 degrees angle of incidence at various door flapdeflection angles 702 according to an embodiment of the disclosure. Asshown in FIGS. 6-12 strength of the landing gear wake 402 reduces as thedoor flap deflection angles 702 increase from, for example, about zeroto about 30 degrees. The landing gear wake 402 may grow at higher doorflap deflection angles 702 (e.g., >30 degrees), indicating an examplenominal door flap deflection angles 702 may be, for example, below 30degrees.

FIG. 13 is an illustration of a graph 1300 showing a wake deficit 1302of the landing gear wake 402 at various door flap deflection angles 702.The wake deficit 1302 is measured with the landing gear door 304 at,without limitation, 8 degrees angle of incidence, the free stream flow602 at, without limitation, Mach 0.17 and Reynolds number (RE) of1265400 according to an embodiment of the disclosure. The graph 1300shows a non-dimensional distance Y from the landing gear door 304 (e.g.,normalized by a chord length of the landing gear door 304) vs. anon-dimensional velocity magnitude. The wake deficit 1302 shows that thedoor flap 308 at the door flap deflection angles 702 of, for example, 12degrees and 14 degrees generates minimum momentum loss in the landinggear wake 402 as shown by curves 1304 and 1306 respectively.

FIG. 14 is an illustration of a graph 1400 showing a lift coefficientC_(L) of the landing gear door 304 vs. door flap deflection angles 702of the door flap 308 in degrees according to an embodiment of thedisclosure. The graph 1400 illustrates that beyond about 15 degrees ofdoor flap deflection angle 702 the lift coefficient C_(L) flattens andthere is substantially no more additional circulation and hencesubstantially no substantial velocity reduction can be obtained aroundthe landing gear strut 322.

FIG. 15 is an illustration of a graph 1500 showing a landing gearwake-wing flap interaction noise reduction due to deploying the landinggear door 304 according to an embodiment of the disclosure compared to alanding gear wake-wing flap interaction noise generated when using anexisting main landing gear door. A curve 1502 shows sound pressure level(SPL) in dB vs. frequency in Hertz (Hz) for noise generated when thelanding gear door 304 is in the landing gear door deployed position 314with the door flap 308 and the leading edge section 306 deflected towardthe landing gear strut in the direction 330. A curve 1504 shows SPL indB vs. frequency in Hz for noise generated without deploying the landinggear door 304. The curve 1502 shows the landing gear wake-wing flapinteraction noise is reduced by about 3-5 dB in the landing gear doordeployed position 314.

FIG. 16 is an illustration of a block diagram of a landing gear doorsystem 1600 (system 1600) according to an embodiment of the disclosure.The system 1600 may have functions, material, and structures that aresimilar to the embodiments shown in FIGS. 3, 5, and 6-12. Therefore,common features, functions, and elements may not be redundantlydescribed here.

The system 1600 may comprise a vehicle 200 such as the aircraft 200, afluid dynamic surface such as the wing flap 328 coupled to the aircraft200, the landing gear structure 302 coupled to the aircraft 200 and thelanding gear door 304. The leading edge section 306 is coupled to thelanding gear door 304 and the door flap 308 may be hinged to the landinggear door 304.

An actuator 1602 is coupled to the landing gear door 304. The actuator1602 is configured to deploy the landing gear door 304 in the landinggear door deployed position 314, the leading edge section 306 in theleading edge deployed position 504 and the door flap 308 in the doorflap deployed position 502 to reduce landing gear wake 402 (FIGS. 4 and5) impinging on the pressure side 326 of the wing flap 328, therebyreducing landing gear wake-wing flap interaction noise generated byinteraction of the landing gear wake 402 from the landing gear strut 322and the landing gear braces 324 with the wing flap 328.

The actuator 1602 may deflect the door flap 308 at various door flapdeflection angles 702 as explained above in the context of discussion ofFIG. 7. The actuator 1602 may comprise, for example but withoutlimitation, a linear hydraulic actuator, a ball screw actuator, or otheractuator.

The controller 1606 may be implemented as, for example but withoutlimitation, a part of an aircraft system, a centralized aircraftprocessor, a subsystem computing module comprising hardware and/orsoftware devoted to the system 1600, or other processor.

The controller 1606 is configured to control the actuation motors 1604to actuate the landing gear door 304 via the actuator 1602 to thelanding gear door deployed position 314, the leading edge section 306 tothe leading edge section deployed position 504 and the door flap 308 tothe door flap deployed position 502 via the actuator 1602 according tovarious operation conditions. The operation conditions may comprise, forexample but without limitation, flight conditions, ground operations, orother condition. The flight conditions may comprise, for example butwithout limitation, landing, or other flight condition. The groundoperations may comprise, for example but without limitation, airbreaking after landing, taxing, parking, or other ground operation. Thecontroller 1606 may be located remotely from the actuation motors 1604,or may be coupled to the actuation motors 1604. In one embodiment, thecontroller 1606 may be placed in a cockpit of the aircraft 200.

The controller 1606 may comprise a processor module 1608 comprisingprocessing logic that is configured to carry out the functions,techniques, and processing tasks associated with the operation of thesystem 1600. In particular, the processing logic is configured tosupport the system 1600 described herein. For example, the processormodule 1608 may direct the actuation motors 1604 to deflect the leadingedge section 306 and the door flap 308 via the actuator 1602.

The processor module 1608 may be implemented, or realized, with ageneral purpose processor, a content addressable memory, a digitalsignal processor, an application specific integrated circuit, a fieldprogrammable gate array, any suitable programmable logic device,discrete gate or transistor logic, discrete hardware components, or anycombination thereof, designed to perform the functions described herein.In this manner, a processor may be realized as a microprocessor, acontroller, a microcontroller, a state machine, or the like. A processormay also be implemented as a combination of computing devices comprisinghardware and/or software, e.g., a combination of a digital signalprocessor and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a digital signal processorcore, or any other such configuration.

The memory module 1610 may comprise a data storage area with memoryformatted to support the operation of the system 1600. The memory module1610 is configured to store, maintain, and provide data as needed tosupport the functionality of the system 1600. For example, the memorymodule 1610 may store flight configuration data, actuation signal(s) foractivation of the actuation motors 1604, the door flap deflection angles702 of the door flap 308, or other data.

In some embodiments, the memory module 1610 may comprise, for examplebut without limitation, a non-volatile storage device (e.g.,non-volatile semiconductor memory, hard disk device, optical diskdevice, and the like), a random access storage device (for example,SRAM, DRAM), or any other form of storage medium known in the art.

The memory module 1610 may be coupled to the processor module 1608 andconfigured to store, for example but without limitation, a database, andthe like. Additionally, the memory module 1610 may represent adynamically updating database containing a table for updating thedatabase, or other application. The memory module 1610 may also store, acomputer program that is executed by the processor module 1608 anoperating system, an application program, tentative data used inexecuting a program, or other application.

The memory module 1610 may be coupled to the processor module 1608 suchthat the processor module 1608 can read information from and writeinformation to the memory module 1610. For example, the processor module1608 may access the memory module 1610 to access the door flapdeflection angles 702, an activation command, or other data.

As an example, the processor module 1608 and memory module 1610 mayreside in respective application specific integrated circuits (ASICs).The memory module 1610 may also be integrated into the processor module1608. In an embodiment, the memory module 1610 may comprise a cachememory for storing temporary variables or other intermediate informationduring execution of instructions to be executed by the processor module1608.

FIG. 17 is an illustration of an exemplary flowchart showing a processfor reducing landing gear wake-wing flap interaction noise according toan embodiment of the disclosure. The various tasks performed inconnection with process 1700 may be performed mechanically, by software,hardware, firmware, computer-readable software, computer readablestorage medium, or any combination thereof. It should be appreciatedthat process 1700 may include any number of additional or alternativetasks, the tasks shown in FIG. 17 need not be performed in theillustrated order, and the process 1700 may be incorporated into a morecomprehensive procedure or process having additional functionality notdescribed in detail herein.

For illustrative purposes, the following description of process 1700 mayrefer to elements mentioned above in connection with FIGS. 1-16. In someembodiments, portions of the process 1700 may be performed by differentelements of the system 1600 such as: the landing gear door 304, the doorflap 308, the leading edge section 306, the actuator 1602 etc. It shouldbe appreciated that process 1700 may include any number of additional oralternative tasks, the tasks shown in FIG. 17 need not be performed inthe illustrated order, and the process 1700 may be incorporated into amore comprehensive procedure or process having additional functionalitynot described in detail herein. Process 1700 may have functions,material, and structures that are similar to the embodiments shown inFIGS. 3, 5, and 6-15. Therefore, common features, functions, andelements may not be redundantly described here.

Process 1700 may begin by deploying a landing gear door such as thelanding gear door 304 comprising a trailing edge such as the trailingedge 310 and a leading edge such as the leading edge 312 (task 1702).

Process 1700 may continue by deflecting toward a landing gear strut suchas the landing gear strut 322 a leading edge section such as the leadingedge section 306 comprising the leading edge 312 and coupled to thelanding gear door 304 (task 1704).

Process 1700 may continue by deflecting toward the landing gear strut322, a door flap such as the door flap 308 comprising the trailing edge310 and hinged to the landing gear door 304 (task 1706).

Process 1700 may continue by reducing a flow velocity on a pressure sideof the landing gear door 304 due to deflecting the leading edge section306 and the door flap 304 (task 1708).

Process 1700 may continue by reducing a landing gear strut noise of thelanding gear strut 322 in response to reducing the flow velocity (task1710).

Process 1700 may continue by reducing a landing gear wake such as thelanding gear wake 402 impinging on a pressure side such as the pressureside 326 of a wing flap such as the wing flap 328 in response toreducing the flow velocity (task 1712). The leading edge section 306reduces separation on the landing gear door 304, and thus reduces thewake deficit 1302. In the door flap deployed position 502, the deflecteddoor flap 308 on the trailing edge 310 causes circulation around thelanding gear strut 322, thereby reducing the local flow velocity 508.Reducing the local flow velocity 508 also reduces viscous losses aroundthe landing gear strut 322, and thus reduces the landing gear wake 402downstream of the landing gear strut 322.

Process 1700 may continue by reducing a landing gear wake-wing flapinteraction noise generated by the interaction of the landing gear wake402 with the wing flap 328 (task 1714).

Process 1700 may continue by increasing a wing flap effectiveness of thewing flap 328 in response to reducing the interaction of the landinggear wake 402 with the wing flap 328 (task 1716).

Process 1700 may continue by reducing a risk of unexpected buffet of thewing flap 328 in response to reducing the interaction of the landinggear wake 402 with the wing flap 328 (task 1718).

FIG. 18 is an illustration of an exemplary flowchart showing a process1800 for configuring a quiet (low noise) landing gear door according toan embodiment of the disclosure. The various tasks performed inconnection with process 1800 may be performed mechanically, by software,hardware, firmware, computer-readable software, computer readablestorage medium, or any combination thereof. It should be appreciatedthat process 1800 may include any number of additional or alternativetasks, the tasks shown in FIG. 18 need not be performed in theillustrated order, and the process 1800 may be incorporated into a morecomprehensive procedure or process having additional functionality notdescribed in detail herein.

For illustrative purposes, the following description of process 1800 mayrefer to elements mentioned above in connection with FIGS. 1-16. In someembodiments, portions of the process 1800 may be performed by differentelements of the system 1600 such as: the landing gear door 304, the doorflap 308, the leading edge section 306, the actuator 1602, etc. Itshould be appreciated that process 1800 may include any number ofadditional or alternative tasks, the tasks shown in FIG. 18 need not beperformed in the illustrated order, and the process 1800 may beincorporated into a more comprehensive procedure or process havingadditional functionality not described in detail herein. Process 1800may have functions, material, and structures that are similar to theembodiments shown in FIGS. 3, 5, and 6-15. Therefore, common features,functions, and elements may not be redundantly described here.

Process 1800 may begin by configuring a landing gear door such as thelanding gear door 304 to deploy to a landing gear deployed position suchas the landing gear deployed position 314 (task 1802).

Process 1800 may continue by coupling a leading edge section such as theleading edge section 306 to the landing gear door 304 (task 1804).

Process 1800 may continue by locating a door flap such as the door flap308 at a percent chord plane of a landing gear door 304 (task 1806).

Process 1800 may continue by hinging the door flap 308 to the landinggear door 304 (task 1808).

Process 1800 may continue by configuring the leading edge section 306and the door flap 308 to deflect toward a landing gear strut such as thelanding gear strut 322 in the landing gear deployed position 314 toreduce a local flow speed near the landing gear strut 322 and minimizewake impinging on a pressure side such as the pressure side 326 of anaerodynamic surface such as the wing flap 328 of an aircraft such as theaircraft 200 such that a landing gear noise and landing gearwake-aerodynamic surface interaction noise are reduced (task 1810).

Process 1800 may continue by coupling the landing gear door to a landinggear structure such as the landing gear structure 302 of an aircraftsuch as the aircraft 200 (task 1812).

In this way, embodiments of the disclosure provide a quiet (reducednoise) landing gear door that reduces a landing gear noise and landinggear wake-aerodynamic surface interaction noise.

Terms and phrases used in this document, and variations thereof, unlessotherwise expressly stated, should be construed as open ended as opposedto limiting. As examples of the foregoing: the term “including” shouldbe read as meaning “including, without limitation” or the like; the term“example” is used to provide exemplary instances of the item indiscussion, not an exhaustive or limiting list thereof; and adjectivessuch as “conventional,” “traditional,” “normal,” “standard,” “known” andterms of similar meaning should not be construed as limiting the itemdescribed to a given time period or to an item available as of a giventime, but instead should be read to encompass conventional, traditional,normal, or standard technologies that may be available or known now orat any time in the future.

Likewise, a group of items linked with the conjunction “and” should notbe read as requiring that each and every one of those items be presentin the grouping, but rather should be read as “and/or” unless expresslystated otherwise. Similarly, a group of items linked with theconjunction “or” should not be read as requiring mutual exclusivityamong that group, but rather should also be read as “and/or” unlessexpressly stated otherwise. Furthermore, although items, elements orcomponents of the disclosure may be described or claimed in thesingular, the plural is contemplated to be within the scope thereofunless limitation to the singular is explicitly stated. The presence ofbroadening words and phrases such as “one or more,” “at least,” “but notlimited to” or other like phrases in some instances shall not be read tomean that the narrower case is intended or required in instances wheresuch broadening phrases may be absent.

The above description refers to elements or nodes or features being“connected” or “coupled” together. As used herein, unless expresslystated otherwise, “connected” means that one element/node/feature isdirectly joined to (or directly communicates with) anotherelement/node/feature, and not necessarily mechanically. Likewise, unlessexpressly stated otherwise, “coupled” means that oneelement/node/feature is directly or indirectly joined to (or directly orindirectly communicates with) another element/node/feature, and notnecessarily mechanically. Thus, although FIGS. 1-3, 4-16 depict examplearrangements of elements, additional intervening elements, devices,features, or components may be present in an embodiment of thedisclosure.

In this document, the terms “computer program product”,“computer-readable medium”, “computer readable storage medium”, and thelike may be used generally to refer to media such as, for example,memory, storage devices, storage unit, or other non-transitory media.These and other forms of computer-readable media may be involved instoring one or more instructions for use by the processor module 1608 tocause the processor module 1608 to perform specified operations. Suchinstructions, generally referred to as “computer program code” or“program code” (which may be grouped in the form of computer programs orother groupings), when executed, enable the system 1600.

As used herein, unless expressly stated otherwise, “operable” means ableto be used, fit or ready for use or service, usable for a specificpurpose, and capable of performing a recited or desired functiondescribed herein. In relation to systems and devices, the term“operable” means the system and/or the device is fully functional andcalibrated, comprises elements for, and meets applicable operabilityrequirements to perform a recited function when activated. In relationto systems and circuits, the term “operable” means the system and/or thecircuit is fully functional and calibrated, comprises logic for, andmeets applicable operability requirements to perform a recited functionwhen activated.

1. A quiet landing gear door comprising: a landing gear door comprisinga trailing edge and a leading edge and operable to deploy to a landinggear door deployed position; a door flap comprising the trailing edgeand hinged to the landing gear door and operable to deflect toward alanding gear strut to a door flap deployed position in response todeployment of the landing gear door; and a leading edge sectioncomprising the leading edge and coupled to landing gear door andoperable to deflect toward the landing gear strut to a leading edgesection deployed position in response to deployment of the landing geardoor.
 2. The quiet landing gear door of claim 1, wherein the leadingedge section in the leading edge section deployed position and the doorflap in the door flap deployed position reduces a flow velocity on apressure side of the landing gear door reducing a landing gear wake-wingflap interaction noise.
 3. The quiet landing gear door of claim 2,wherein a nominal door flap deflection angle is below 30 degrees.
 4. Thequiet landing gear door of claim 2, wherein the leading edge section inthe leading edge section deployed position and the door flap in the doorflap deployed position reduce the landing gear wake-wing flapinteraction noise generated by a landing gear wake-wing flapinteraction.
 5. The quiet landing gear door of claim 4, wherein theleading edge section in the leading edge deployed position and the doorflap in the door flap deployed position reduce a landing gear wakeimpinging on a pressure side of a wing flap reducing the landing gearwake-wing flap interaction and the landing gear wake-wing flapinteraction noise.
 6. The quiet landing gear door of claim 5, whereinreducing the landing gear wake-wing flap interaction increaseseffectiveness of the wing flap.
 7. The quiet landing gear door of claim4, wherein reducing the landing gear wake-wing flap interaction reducesa risk of unexpected buffet of the wing flap.
 8. The quiet landing geardoor of claim 1, wherein the door flap is located at a percent of achord plane of the landing gear door.
 9. The quiet landing gear door ofclaim 1, wherein the landing gear door is coupled to a landing gearstructure of an aircraft.
 10. A method for reducing landing gear noise,the method comprising: deploying a landing gear door comprising atrailing edge and a leading edge; deflecting toward a strut a leadingedge section comprising the leading edge and coupled to the landing geardoor; deflecting toward the strut a door flap comprising the trailingedge and hinged to the landing gear door; and reducing a flow velocityon a pressure side of the landing gear door due to deflecting theleading edge section and the door flap.
 11. The method of claim 10,further comprising reducing a landing gear strut noise of the landinggear strut in response to reducing the flow velocity.
 12. The method ofclaim 11, further comprising reducing a landing gear wake-wing flapinteraction noise generated by an interaction of a landing gear wakewith a wing flap.
 13. The method of claim 12, wherein the door flap islocated at a percent of a chord plane of the landing gear door.
 14. Themethod of claim 11, further comprising reducing a landing gear wakeimpinging on a pressure side of a wing flap in response to reducing theflow velocity.
 15. The method of claim 14, further comprising reducingan interaction of the landing gear wake with the wing flap in responseto reducing the flow velocity.
 16. The method of claim 15, furthercomprising increasing a wing flap effectiveness of the wing flap inresponse to reducing the interaction of the landing gear wake with thewing flap.
 17. The method of claim 15, further comprising reducing arisk of unexpected buffet of the wing flap in response to reducing theinteraction of the landing gear wake with the wing flap.
 18. A methodfor configuring a quiet landing gear door, the method comprising:configuring a landing gear door to deploy to a landing gear deployedposition; coupling a leading edge section to the landing gear door;hinging a door flap to the landing gear door; and configure the leadingedge section and the door flap to deflect toward a landing gear strut inthe landing gear deployed position to reduce a local flow speed near thelanding gear strut and minimize a wake impinging on a pressure side ofan aerodynamic surface of an aircraft such that a landing gear noise anda landing gear wake-aerodynamic surface interaction noise are reduced.19. The method of claim 18, further comprising locating the door flap ata percent chord plane of the landing gear door.
 20. The method of claim18, further comprising coupling the landing gear door to a main landinggear structure of the aircraft.